1. Field of the Invention
This invention relates to the field of data communication equipment, and in particular to artificial inductors in data access arrangements.
2. Background Art
Telephone systems were originally designed for simple voice communication. As new technologies have emerged, methods have been devised to provide more advanced voice communication functions, as well as to transmit other types of information over telephone lines. These methods typically require the connection of electronic equipment, other than the voice telephone set, to the telephone line. Examples of such equipment include computer modems, facsimile ("fax") machines, answering machines, voice mail systems, phone patches, automatic number identification (ANI) or "Caller ID" systems, and advanced telephone systems.
The electrical characteristics of signals present within the above equipment often differ from the electrical characteristics permitted on a standard twisted-pair telephone line used to connect the equipment to a central office (CO) of the local telephone service provider. An interface circuit referred to as a data access arrangement (DAA) is utilized to couple the equipment to the telephone line. The data access arrangement typically provides isolation, impedance matching, and sometimes amplification, filtering and control functions.
Unfortunately, the specifications for data access arrangements may differ from region to region or country to country to meet the electrical operating parameters of the respective central office. Therefore, a particular data access arrangement has utility only in those countries where the operating specifications are met. The relationship between the data access arrangement and the central office is more clearly understood with reference to a sample data access arrangement as illustrated in FIG. 1.